I was reading through the Newegg reviews and quite a few of them mentioned heating issues with SLi configurations.
Thanks for the responses. Looks like I'll be waiting this one out as well. I'm strictly an nVidia guy and if new AMD cards means lower nVidia prices, I'm all for that.
I wanted to get my own assessment of "hot SLI" issues, with only time to check on my own favorite for this year: The MSI cards. I might have looked at reviews for my GTX 970s, but I scanned through some for the GTX 980 "Gaming" card.
Nobody was complaining much about temperatures, but as usual, customer-reviews come from folks inclined to measure the thermals with "daily usage" and games.
In other sources -- forum discussions about SLI -- there is a familiar profile that emerges with two big graphics cards installed in slots that leave less than an inch of space between them. Typically, the top card will run under stress-test loads a full 10C higher than the card below. On my 970s, I've seen the delta between 7 and 10C, depending on the test and how long it runs.
Among enthusiasts who don't pay a lot of attention to airflow for WHATEVER cooling strategy they employ, temperatures are going to be higher than for those who do pay attention at the outset.
Here, I have a 200mm BitFenix Spectre Pro side-panel intake fan rated at 144 CFM at top speed blowing on these cards. It's pushing air all over those cards -- top, bottom, upper side, lower side. And the dual "Twin Frozr" fans or whatever they're called push air in the heatpipe cooler fins in all directions. The fins are arrayed horizontally on the cards, front to back.
And this was the advantage posed by advocates of the "reference-card" design and barrel-fan, which blows air out the card-rear vented PCI-slot.
For the dual-fan designs, I can imagine some low-tech enhancements, provided you don't use any slot between the two SLI'd cards for another expansion card. You would remove the two PCI slot-covers, each just above each successive graphics card. You might then find a way to channel air up and over the top of each card and force that air out these two open PCI slots. But there's just not a lot of room to make such enhancements in the space between the cards.
If I finally decide to "act" on my impulse to enhance SLI cooling without water-blocks, I'll post it here later. But if one could close the 10C gap in temperatures between upper and lower cards, it would be an achievement for this particular topic.